Low Carb Cookworx with husband and wife Drs. Michael and Mary Dan Eades was one of my favorite LC shows. It is no longer on in this area.
As a matter of fact, while I was losing my weight I used to get up at 4am when the show aired in this area and sit and do my recliner bike while watching the show.

I suggest using the sweet dumpling squash for those things you mention as it seems to be the closest to a potatoes color and texture. The taste unlike celery root is just like potatoe.